



 
Hi, Suppose the length of the longer of the parallel sides is $L$ units, the length of the shorter of the parallel sides is $S$ units and the lengths of the other two sides is $x$ units as in the diagram below. The length of the line segment BC is $\large \frac{LS}{2},$ can you see why? Thus for the right triangle $ABC$ you know the lengths of two of its sides and Pythagoras Theorem will give you $h,$ the length of the third side. Penny  


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